This invention relates to supplying augmenting compressed air and/or cooling media to a combustion turbine via a separate compressor. For the case of cooling media supply, the media may be conditioned, e.g., cooled and/or humidified.
Most combustion turbines use air bled from one or more locations of the integral compressor to provide for cooling and sealing in the turbine component. Air bled from the compressor for this purpose may be routed internally through the bore of the compressor-turbine rotor or other suitable internal passages to the locations that require cooling and sealing in the turbine section. Alternatively, air may be routed externally through the compressor casing and through external (to the casing) piping to the locations that require cooling and sealing. Many combustion turbines utilize a combination of the internal and external routing of cooling and sealing air to the turbine component. Some combustion turbines use heat exchangers to cool the cooling and sealing air routed through the external piping before introduction into the turbine component.
The output or capacity of a combustion turbine usually falls off with increasing temperature at the inlet to the compressor component. Specifically, the capacity of the compressor component to supply air to the combustion process and subsequent expansion through the turbine is reduced as the compressor inlet temperature is increased (usually due to increased ambient temperature). Thus, the turbine component and combustion component of the combustion turbine usually have the capability to accept more compressed air than the compressor component can supply when operating above a certain inlet temperature.
In accordance with one embodiment of this invention, the supply of pressurized air to the combustion and turbine components is augmented by use of an external compressor when the capability of the integral compressor is reduced, thereby increasing the output of the combustion turbine or combined cycle power plant.
There are, however, several ways to utilize the external compressor. One way is to insert compressed ambient air into the combustion turbine flow path at the exit of the compressor component and/or in the combustion component before fuel addition. (This will be referred to as xe2x80x9cpure augmentationxe2x80x9d air supply).
Another way of using the external compressor is to incorporate it into a system for supplying conditioned cooling and sealing media to the turbine component. This may be done combined with the pure augmentation method described above, or separately in the event the pure augmentation method is not utilized. The supply of cooling media by the external supply system reduces that which would normally be supplied through extraction from the integral compressor component of the combustion turbine, allowing more air from the integral compressor to be directed to the combustion component, thereby increasing output.
In its broader aspects, therefore, the invention relates to a land based gas turbine apparatus comprising an integral compressor; a turbine component having a combustor to which air from the integral compressor and fuel are supplied; and a generator operatively connected to the turbine for generating electricity; wherein hot component parts in the turbine component are cooled at least partially by air or other cooling media supplied by an external compressor.
In another aspect, the invention relates to a method of insuring peak power capability for a gas turbine power plant including an integral compressor, a turbine component including a combustor and a generator, wherein hot gas path parts in the turbine component are cooled by cooling air, the method comprising supplying compressed air to said combustor from the internal compressor; and supplying at least a portion of the cooling air or other cooling media to the hot gas path parts in the turbine component from an external compressor.